Two things.
One, I need context for this thread discussion because I've been out of the loop for a hot minute. Please stop what, where and why?
Two, raise your hands if you remember a guy named Teron Gorefiend -- the example that Death Knights have been wielding fire magicks longer than they've wielded frost in the Warcraft mythos.
Okay, sure, you can say that Gorefiend wasn't a Scourge death knight, so he shouldn't count, despite inspiring such abilities as Gorefiend's Grasp. Then I would remind you of Thane Korth'azz, one of the Four Horsemen who could summon fire and meteors at will. Fire powers are not beyond a Scourge-born DK to wield within the lore, even without Bolvar.
The main reason I would disagree with it, however, is that we have plenty of fire-wielding classes, with Demon Hunters in particular running pretty far with the hellfire motif and Retadins taking the fire-wielding knight the other way. Warlocks and Mages already have enough trouble distinguishing their fire specs. Kinda makes it redundant for DKs.